Angular AOT Build: Internal error: unknown identifier undefined

This part of the application caused the problem:

export function windowFactory(): any {
    return window;
}

providers: [{
    provide: Window,
    useFactory: windowFactory
}],

Github: This fails with AoT compiler in Angular CLI, because Window (the browser window) is an interface

Had the same error when trying to provide Date for injection instead of an injection token.

So I did:

providers: [
    { provide: Date, useValue: new Date() }
  ]

and changed it to

providers: [
    { provide: NOW, useValue: new Date() },
  ],

where NOW is defined in the service that depends on it like this

export const NOW = new InjectionToken<Date>('now');

All documented on the Angular site.

Just for completeness since I stumbled upon the same error in a different context. The error occurred in my build when using an upgraded angularjs service class that was exported as default

// Service definition
export default class MyService { /* Registered AngularJS service here */ }

// Module
import MyService from './my-service'

// Upgrade 
export function myServiceFactory(i:any) {
  return i.get('myService');
}

// ngUpgraded Angular main module 
@NgModule({
  providers: [
    { provide: MyService, useFactory: myServiceFactory, deps: ['$injector'] }
  ]
})

Removing the default export resolved the issue.

For me, I created a base class for my services that uses HttpClient.

The base class and the sub class were marked as Injectable.

I removed Injectable from the base class and it solved the issue.

I'm running on Angular 11 (upgraded over time from 7). I just received this error but it was because I accidentally reverted my tsconfig.json file. The enableIvy line in angularCompilerOptions was reverted to the following setup that caused the error (for me at least):

  "angularCompilerOptions": {
    "fullTemplateTypeCheck": false,
    "strictInjectionParameters": true,
    "enableIvy": false
  }

With Angular 11, the enableIvy line should be removed. My working angularCompilerOptions became:

  "angularCompilerOptions": {
    "fullTemplateTypeCheck": false,
    "strictInjectionParameters": true
  }

I'm pretty sure the upgrade to 11 set this correctly but I messed up a revert.

This happened to my due to Class Inheritance, where both the BaseClass and the DriveClass had @Injectable decorator.

@Injectable({
  providedIn: 'root'
})
export class BaseService { 
  ... 
}

@Injectable({
  providedIn: 'root'
})
export class DriveService extends BaseService {
 ... 
}

Removing the @Injectable from the BaseService solved the problem.

I faced this problem twice and search for it twice. I just put my answer here for myself in future :)

In my case, this problem occurs when I create 2 projects:

• my-lib (which contains common components that can be built as a library and publish to npmjs)
• my-app (main application)

This is what I did:

1. In my-lib, there is one class:

@Injectable()
export class MyFirstService implement IMyFirstService {
}

2. In my-app, I declare one module which consume the service above:

@NgModule({
    providers: [
        {
            provide: MY_FIRST_SERVICE_INJECTION_TOKEN,
            useClass: MyFirstService
        }
    ]
})
export class MyLittleModule {
}

3. When I ran ng build --prod, the exception occurs.

This is how I fix:

• Remove the Injectable() annotation from MyFirstService class. The exception has gone.

Finally, I just want to say to my future me:

• Hey myself, if you read this, that means this is nth times you forgot about this painful issue. :v

Check your templates maybe you used a variable in the template which is not defined in the component

Expanding on im4ever's answer, I ran into this same issue. It only showed up when doing a build when setting the configuration, not on ng serve or just ng build which led me to believe that it is an AOT issue.

When registering a service using a factory method, which I was doing so that I could inject localStorage, I had my module setup like this (shortened for brevity).

providers: [
    {provide: StateService, useFactory: provideStateService}
  ],

What I did to fix the issue was remove the @Injectable({}) decorator that I also had on the StateService class definition. Once I removed that, errors all went away.

Had this problem while running ng build --prod for Angular 7.1.4, so I removed the @Injectable that Karthi Coimbatore recommended for a TooltipService I created to use Angular Material tooltip's positions.